Laminates of plastics resin films, such as polyethylene, polypropylene, polyvinyl chloride, nylon and the like, and metallic foils, such as aluminum, lead, steel and the like, are employed for numerous purposes, including labels, packaging materials, and the like. In such laminates, the materials cooperate to provide properties as a unit which the individual components fail to provide as single layer materials. Thus, the metallic foil, especially aluminum foil, provides oxygen barrier properties which plastics resin films cannot provide, while the films provide surface corrosion resistance for the surfaces of the foil.
Typically, foil-film laminates are produced by adhesive bonding, normally under conditions of heat and pressure.
While the desired properties for both the foil and film layers requires only relatively thin material layers, it is extremely difficult to work with such thin layers under commercial production limitations of equipment and speed.
U.S. Pat. No. 3,589,975 discloses a method in which an unmounted plastics resin film layer and aluminum foil layer are passed between a pair of work rolls in a rolling mill. At the work rolls, both the film and the foil are reduced significantly in thickness, thus increasing the yield of sheet material for a given weight of material input, and with bonding of the plastics resin film to the aluminum foil occurring at the work rolls.
Subsequently, it has been found that the adhesion of the film and foil in the process described in U.S. Pat. No. 3,589,975 is insufficient for many commercial uses. There remains, however, a need for plastics resin film-metallic foil laminates of reduced thickness and with acceptable adherence.